Immunoglobulins and hypersensitivity Flashcards

1
Q

What is the most common immunoglobulin?

A

IgG - 75%

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2
Q

What is the function of IgG?

A

Enhance phagocytosis of bacteria and viruses
Fixes complement and passes to foetal circulation

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3
Q

What is the shape of IgG?

A

Monomer

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4
Q

What is the 2nd most common immunglobulin?

A

IgA - 15%
Most commonly produced but lower serum concentration than IgG

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5
Q

What is the function of IgA?

A

Provides localised protection of mucous membranes

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6
Q

Where is IgA found?

A

Main Ig in breast milk
Sigestive, respiratory and urogenital tracts

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7
Q

What is the shape of IgM?

A

Pentamer

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8
Q

What is the function of IgM?

A

Fixes complement

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9
Q

What is the clinical significance of IgM?

A

First immunglobulin secreted in response to infection
Anti A and B antibodies

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10
Q

What is the function of IgD?

A

Activation of B cells

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11
Q

What is the function of IgE?

A

Mediates type 1 hypersensitivity reactions
Immunity to parasites

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12
Q

How is IgE synthesised?

A

Plasma cells

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13
Q

What does IgE bind to?

A

Fc receptors on mast cells and basophils

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14
Q

What is the least common immunoglobulin?

A

IgE

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15
Q

What are type 1 hypersensitivity reactions?

A

Anaphylactic
Atopic

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16
Q

What is the mechanism of type 1 reactions?

A

Antigen reacts with IgE bound to mast cells

17
Q

What are type 2 hypersensitivity reactions?

A

Cell bound

18
Q

What is the mechanism of type 2 hypersensitivity reactions?

A

IgG or IgM binds to antigen on cell surface

19
Q

What are some examples of type 2 hypersensitivity reactions?

A

Autoimmune haemolytic anaemia
ITP
Pernicious anaemia
Acute haemolytic transfusion reaction
Rheumatic fever
Goodparture’s syndrome
Pemphigus and pemphigoid

20
Q

What are type 3 hypersensitivity reactions?

A

Immune complex

21
Q

What is the mechanism of type 3 hypersensitivity reactions?

A

Free antigen and antibody (IgG, IgA) combine

22
Q

What are some examples of type 3 hypersensitivity?

A

Serum sickness
SLE
Post streptococcal GN
Extrinsic allergic alveolitis

23
Q

What are type 4 hypersensitivity reactions?

A

Delayed hypersensitivity

24
Q

What is the mechanism of type 4 hypersensitivity reactions?

A

T cell mediated

25
Q

What are some examples of type 4 hypersensitivity?

A

TB
GvHD
Allergic contact dermatitis
Scabies
MS
Guillian Barre syndrome

26
Q

What is the mechanism type 5 hypersensitivity reactions?

A

Antibodies bind to cell surface receptors and stimulate or block

27
Q

What are some examples of type 5 hypersensitivity?

A

Grave’s disease
Myasthenia